Metal-filament lamp.



W. R. WHITNEY.

METAL FILAMENT LAMP.

APPLICATION FILED AUG.19, 1907.

1,0133915, Patented Jan. 9. 1912 M ZTNESEEB' INVENTUH I" q a I UNITEDSTATES PATENT oFFio r.

WILLIS R. WHITNEY, OF SCHENECTADY, NEW YORK, AS SIGNOR TC GENERALELECTRIC COMPANY, A CORPORATION OF ITEW' YORK.

METAL FILAMENT LAMP.

To all whom it may concern:

Be. it;known that- I, WILLIS, R. WHITNEY,

- a citizen of the United States, residing at Schenectady, county "ofSchenectady, State of 'New York, have invented certain new filamentlamps.

It comprises means for protecting filaments against excessivelongitudinal stress. Lamp filaments of tungsten, molybdenum, and othersimilar refractory metals. can be operated at very high temperatures inlamps,

but when so operated, are in a somewhat soft and pliant condition. andthereto-re re quire supporting means to prevent distortion of thefilament and shortcn'cuits m the lamp. It is common practice to hold thefilaments in their proper position by means of resilient supportsengaging with the ends of the filament loops. These supports are putunder tension when the lamp is assembled and the tension is intended tobe just sufficient to hold the filament straight when hot, but notsufiicient to tear the filament in two, either during normal burning orafter the filament has shrurlc somewhat in aging, as some of theselllllllltBIl-lii seem to do. The tension exerted by the filamentsupports is supposed to be uniform for all the filaments, but inpractice it varies somewhat with the skill of the girl who assembles thelamps.

The present invention aims to protect filaments against excessive stresby the use of anchoring wires having a cmtract-ed or weakened portionwhich will bend and allow the end of the wire to tip in case the tensionon the filament becomes dangerous.

The details of my invention will be better understood by reference tothe accompanying drawing, in which- Figure l is a perspective view of acompleted lamp; Fig. 2- is an enlarged elevation of one current supplywire; Fig. 3 is a modified form of supply wire, and, Fig. 4 is a detailshowing the current supply wires grouped about the central pedestal.

The metal filaments 1 may be of tungsten or other suitable metal andsupported at their ends by refractory springs 2 of tungsten or tantalum.These springs may be conven-.

iently mountedin-theenddf a glass pedestal Specifice'ttion of LettersPatent.

3 and are so adjusted as to maintain the filament loops'in a tautcondition when hot, without subjecting them to undue stress dur-Patented Jan. 9,1912. Application filed August 19, 1907. Serial No.389,312.

ing normal contraction. The lower ends of the metal filaments areweldedor pasted to current supply-wires a disposed radially in a central hub 5of glass. These radial current supply wires at may be cylindrical, as

shown in Fig. 9., and provided with a weakened portion 6 made by dentingor otherwisecontracting the wire. inasmuch as the heat distribution inthe wire is good, this contracted portion will not burn out even thoughthe crosssectien may be consider-f" 1 ably less than other parts of thesupply- -wire. If, new, by any chance the lamp has i been improperlyassembled, and one or moreor the spring supports 2 have been placedunder too greata tension,the abnormal stress on the filaments willproduce bending of the current supply-wires at the point 6 and thedanger of filament rupture will be removed.

I do not rely on the elasticity 0r resiliency of this contracted part ofthe current supply-wire to' secure spring tension on the filament, but Imake use of it merelyas a' safety device which bends in cases where thefilament might otherwise be ruptured. The

current supply-wire may be of platinum,

nickel, nickel-alloy, copper, or other suitable metal.

The modification illustrated in Fig. 3 consists of a flat ribbon 7, sayof nickel, sealed into the glass hub 5 of the pedestal and given apartial or complete twist at the point 8 between the pedestal and thefila ment 1. This twist turns the supply-\ ire so that it mechanicallyweak in the dir ction of the filament and is thereby capable of actingas a safety device in the same way as does the contracted wire of Fig.2.

I make no claim in this application to the refractory springs 2 oftungsten since such resilient supports form the subject matter of mycopending application, Ser. No. 378,932, filed June 14, 1907.

W hat I claim as new, and desire to secure ioo by Letters Patent of theUnited States,

filament from dangerous longitudinal st1'ess.

2. In a lamp, a fragile metal filament,

sion to which the filament can be-subjected' by undergoing permanentdeformation whenever tension on the filament exceeds a certain amount.

3. In a lamp, a metal filament, and a current supply wire thereformechanically weak to stresses along the filament and adapted to take apermanent pend to protect the filament from mechanical-rupture Wheneverthe stress on the filament becomes excessive.

4. The combination of a filament loop, a resilient support for one endof'the loop, and an anchorage for the other endof the loop capable ofdeformation under the pull of the filament to protectthe filament fromdangerous tension.

5. The combination of a fragile filament loop, a resilient support forone end of the loop, and means at the other end of the loop adapted tocompensate for improper adjustment of said resilient support byundergoing permanent deformation as a result of force exerted by thefilament.

6. The combination of a filament which becomes soft during normalrunning, resilient means for holding said filament in position, and ananchorage for said filament capable of taking a permanent bend underforce exerted by the filament to protect said filament from dangerouslongitudinal stress.

7. The combination of a plurality of looped filaments, resilientsupports for said filaments, rand current supply -wires con nected withsaid filaments and each having a contracted portion for protecting itsfilament from dangerous longitudinal stress by :undergoing permanentdeformation under force exerted by the filament.

S. The combination with a filament suitably supported at one endofsupporting means for the other end of the filament adapted to protectsaid filament from dangerous longitudinal stress by undergoing permanentdeformation under the pullof the filament.

5). Thecombination with a fragilefilament loop suitably supported atoneend of supporting means for the other end of the loop mechanically weakto longitudinal' stresses in the filament so as to be capable, byundergoing permanent deformation as a result of force exerted by thefilament of protecting the filament from rupture.

In witness whereof, I have hereunto set my hand this 17th day of August,1907.

, WILLIS R. WHITNEY.

lYit-nesses BENJAMIN B. HULL, HELEN ()nronn.

